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Wide Companions to Hipparcos Stars within 67 pc of the Sun
A catalog of common-proper-motion (CPM) companions to stars within 67 pcof the Sun is constructed based on the SUPERBLINK proper-motion survey.It contains 1392 CPM pairs with angular separations 30'' < ρ <1800'', relative proper motion between the two components less than 25mas yr-1, and magnitudes and colors of the secondariesconsistent with those of dwarfs in the (MV , V - J) diagram.In addition, we list 21 candidate white dwarf CPM companions withseparations under 300'', about half of which should be physical. Weestimate a 0.31 fraction of pairs with red dwarf companions to bephysical systems (about 425 objects), while the rest (mostly wide pairs)are chance alignments. For each candidate companion, the probability ofa physical association is evaluated. The distribution of projectedseparations s of the physical pairs between 2 kAU and 64 kAU followsf(s)vprops -1.5, which decreases faster than Öpik's law.We find that solar-mass dwarfs have no less than 4.4% ± 0.3%companions with separations larger than 2 kAU, or 3.8% ± 0.3% perdecade of orbital separation in the 2-16 kAU range. The distribution ofmass ratio of those wide companions is approximately uniform in the 0.1< q < 1.0 range, although we observe a dip at q ~= 0.5 which, ifconfirmed, could be evidence of bimodal distribution of companionmasses. New physical CPM companions to two exoplanet host stars arediscovered.
| Common proper motion stars in the AGK 3
A search was made of common-proper-motion (CPM) systems among AGK 3stars. The selection of physical systems was based upon the ratiobetween the angular separation (rho) and the proper motion (mu); the CPMstars found are presented in two tables. Table I lists systems withrho/mu less than 1000 years. It contains 326 entries, and the proportionof optical pairs is estimated to be 1 percent. Table II lists systemswith rho/mu in the range 1000 to 3500 years; it contains 113 systems,but only 60 percent of them are physical. Nevertheless, these systemsoften have separations larger than 10,000 AU and are the mostinteresting for the study of the tail of the distribution function ofthe semimajor axes.
| A sample of solar-type stars of known age
A sample of field F and G dwarfs of known ages is presented. All thedwarfs are secondaries of visual binaries in which the temperature andgravity of the hotter primary has been estimated from Stromgrenphotometry, and its age derived from reference to isochrones. This ageis taken to apply to the secondary. Even in the case of F-typesecondaries, which themselves have measured Stromgren indices, it ismuch better to estimate ages from the primaries as it is demonstratedthat use of isochrones to determine age of stars not far evolved fromthe main sequence can lead to significant systematic overestimates ofages when the photometric measurements have typical random errors. Anumber of systems in which photometry is available for both componentshave primaries which appear much younger than the secondaries,suggesting a need for further investigation.
| UVBY Bet study of A-and F-type visual binaries. II.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978AJ.....83.1646M&db_key=AST
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